Inappropriate documentation of heparin allergy in the medical record because of misdiagnosis of heparin-induced thrombocytopenia: frequency and consequences

Quality improvement approaches to heparin-induced thrombocytopenia: a scoping review

Background

Heparin-induced thrombocytopenia (HIT) is a relatively uncommon condition characterized by 2 exceedingly common phenomena in hospitalized patients: thrombocytopenia and heparin exposure. Consequently, HIT is frequently overdiagnosed and inappropriately treated. These issues are the focus of many quality improvement (QI) initiatives.

Objectives

In this scoping review, we identified and characterized all published QI studies on improving the diagnosis and management of HIT.

Methods

We conducted a systematic literature search through April 2022 for studies reporting on QI interventions regarding the diagnosis, treatment, and/or prevention of HIT.

Results

Thirty studies were included in the final review. Studies were separated into 5 groups based on the focus of the interventions: increasing HIT recognition, reducing HIT incidence, reducing HIT overdiagnosis, promoting safer HIT management, and creating HIT task forces. Nine studies focused on the implementation of 4Ts score calculator into electronic medical record orders for HIT testing, while only 1 evaluated the impact of reducing unfractionated heparin use in favor of low-molecular-weight heparin. Six studies focused on the implementation of direct thrombin inhibitor management protocols, while none evaluated the use of alternative anticoagulants in HIT management.

Conclusion

The bulk of published HIT QI research focused on reducing overdiagnosis and promoting safer direct thrombin inhibitor therapy, while minimal attention has been devoted to HIT prevention and the use of evidence-based alternative HIT therapies.

Applications of Artificial Intelligence in Thrombocytopenia

Thrombocytopenia is a medical condition where blood platelet count drops very low. This drop in platelet count can be attributed to many causes including medication, sepsis, viral infections, and autoimmunity. Clinically, the presence of thrombocytopenia might be very dangerous and is associated with poor outcomes of patients due to excessive bleeding if not addressed quickly enough. Hence, early detection and evaluation of thrombocytopenia is essential for rapid and appropriate intervention for these patients. Since artificial intelligence is able to combine and evaluate many linear and nonlinear variables simultaneously, it has shown great potential in its application in the early diagnosis, assessing the prognosis and predicting the distribution of patients with thrombocytopenia. In this review, we conducted a search across four databases and identified a total of 13 original articles that looked at the use of many machine learning algorithms in the diagnosis, prognosis, and distribution of various types of thrombocytopenia. We summarized the methods and findings of each article in this review. The included studies showed that artificial intelligence can potentially enhance the clinical approaches used in the diagnosis, prognosis, and treatment of thrombocytopenia.

A machine-learning model for reducing misdiagnosis in heparin-induced thrombocytopenia: A prospective, multicenter, observational study

BACKGROUND

Diagnosing heparin-induced thrombocytopenia (HIT) at the bedside remains challenging, exposing a significant number of patients at risk of delayed diagnosis or overtreatment. We hypothesized that machine-learning algorithms could be utilized to develop a more accurate and user-friendly diagnostic tool that integrates diverse clinical and laboratory information and accounts for complex interactions.

METHODS

We conducted a prospective cohort study including 1393 patients with suspected HIT between 2018 and 2021 from 10 study centers. Detailed clinical information and laboratory data were collected, and various immunoassays were conducted. The washed platelet heparin-induced platelet activation assay (HIPA) served as the reference standard.

FINDINGS

HIPA diagnosed HIT in 119 patients (prevalence 8.5%). The feature selection process in the training dataset (75% of patients) yielded the following predictor variables: (1) immunoassay test result, (2) platelet nadir, (3) unfractionated heparin use, (4) CRP, (5) timing of thrombocytopenia, and (6) other causes of thrombocytopenia. The best performing models were a support vector machine in case of the chemiluminescent immunoassay (CLIA) and the ELISA, as well as a gradient boosting machine in particle-gel immunoassay (PaGIA). In the validation dataset (25% of patients), the AUROC of all models was 0.99 (95% CI: 0.97, 1.00). Compared to the currently recommended diagnostic algorithm (4Ts score, immunoassay), the numbers of false-negative patients were reduced from 12 to 6 (-50.0%; ELISA), 9 to 3 (-66.7%, PaGIA) and 14 to 5 (-64.3%; CLIA). The numbers of false-positive individuals were reduced from 87 to 61 (-29.8%; ELISA), 200 to 63 (-68.5%; PaGIA) and increased from 50 to 63 (+29.0%) for the CLIA.

INTERPRETATION

Our user-friendly machine-learning algorithm for the diagnosis of HIT (https://toradi-hit.org) was substantially more accurate than the currently recommended diagnostic algorithm. It has the potential to reduce delayed diagnosis and overtreatment in clinical practice. Future studies shall validate this model in wider settings.

FUNDING

Swiss National Science Foundation (SNSF), and International Society on Thrombosis and Haemostasis (ISTH).

Heparin-induced thrombocytopenia and cardiovascular surgery

Clinicians generally counsel patients with a history of heparin-induced thrombocytopenia (HIT) to avoid heparin products lifelong. Although there are now many alternative (nonheparin) anticoagulants available, heparin avoidance remains challenging for cardiac surgery. Heparin is often preferred in the cardiac surgery setting based on the vast experience with the agent, ease of monitoring, and reversibility. To "clear" a patient with a history of HIT for cardiac surgery, hematologists must first confirm the diagnosis of HIT, which can be challenging due to the ubiquity of heparin exposure and frequency of thrombocytopenia in patients in the cardiac intensive care unit. Next, the "phase of HIT" (acute HIT, subacute HIT A/B, or remote HIT) should be established based on platelet count, immunoassay for antibodies to platelet factor 4/heparin complexes, and a functional assay (eg, serotonin release assay). As long as the HIT functional assay remains positive (acute HIT or subacute HIT A), cardiac surgery should be delayed if possible. If surgery cannot be delayed, an alternative anticoagulant (preferably bivalirudin) may be used. Alternatively, heparin may be used with either preoperative/intraoperative plasma exchange or together with a potent antiplatelet agent. The optimal strategy among these options is not known, and the choice depends on institutional experience and availability of alternative anticoagulants. In the later phases of HIT (subacute HIT B or remote HIT), brief intraoperative exposure to heparin followed by an alternative anticoagulant as needed in the postoperative setting is recommended.

Impact of a multidisciplinary workflow on safety and management of patients with heparin-induced thrombocytopenia

PURPOSE

Heparin-induced thrombocytopenia (HIT) is a serious complication of heparin administration. Management strategies are complex and include discontinuing heparin products, initiating alternative anticoagulants, interpreting laboratory test results, documenting heparin allergies, and providing patient education. Medication error reports and a retrospective review conducted at an academic medical center revealed an opportunity for a quality improvement initiative and led to the creation of a multidisciplinary workflow for the management of HIT. In a pre-post study, the impact of the multidisciplinary workflow on the safety and management of HIT was evaluated.

METHODS

The preimplementation group consisted of adult patients tested for suspected HIT from April 4, 2014, through May 31, 2016; the postimplementation group consisted of adult patients tested from November 1, 2016, through October 31, 2018. The primary outcome was the incidence of heparin product administration while HIT testing was ongoing. The secondary outcome was the rate of appropriate heparin allergy documentation.

RESULTS

The incidence of heparin product administration while HIT testing results were pending was significantly reduced, from 54.2% to 20.0% (P < 0.001), after workflow implementation. The rate of appropriate heparin allergy documentation significantly increased, from 95.0% to 100% (P < 0.001).

CONCLUSION

Implementation of a multidisciplinary workflow for the management of HIT significantly reduced the incidence of heparin administration while testing was ongoing and improved the rate of appropriate heparin allergy documentation.

Ascidian-Inspired Heparin-Mimetic Magnetic Nanoparticles with Potential for Application in Hemodialysis as Recycling Anticoagulants

In the present study, heparin-mimetic magnetic nanoparticles (HMNPs), which might be used as recycling anticoagulants, were synthesized by coating heparin-mimetic sodium alginate (HLSA) on the surface of iron oxide magnetic nanoparticles (MNPs), using 3,4,5-trihydroxyphenylalanine (TOPA) as a biological adhesive. HLSA was successfully immobilized on the MNP surface, as revealed by Fourier transform infrared spectroscopy and thermal gravimetric analysis, and the core (MNP)-shell (TOPA, HLSA) structure was confirmed by transmission electron microscopy observations. In addition, in vitro studies of protein adsorption, blood clotting time, and contact activation confirmed that the blood compatibility of the HMNP was significantly enhanced compared with the bare MNP. The improved hemocompatibility was attributed to the introduction of the multiple heparin-mimetic groups (-SO₃Na, -COONa, and -OH). In addition, the HMNP showed outstanding recycle stability and, thus, can be reused if needed. The synthesized HMNP appeared to be a suitable biomaterial to safely replace heparin as an anticoagulant in patients undergoing long-term hemodialysis.

Heparin-induced thrombocytopenia (HIT): Review of incidence, diagnosis, and management

Heparin-induced thrombocytopenia (HIT) is a life and limb-threatening complication of heparin exposure. Here, we review the pathogenesis, incidence, diagnosis, and management of HIT. The first step in thwarting devastating complications from this entity is to maintain a high index of clinical suspicion, followed by an accurate clinical scoring assessment using the 4Ts. Next, appropriate stepwise laboratory testing must be undertaken in order to rule out HIT or establish the diagnosis. In the interim, all heparin must be stopped immediately, and the patient administered alternative anticoagulation. Here we review alternative anticoagulation choice, therapy alternatives in the difficult-to-manage patient with HIT, and the problem of overdiagnosis.

The risk of major bleeding in patients with suspected heparin-induced thrombocytopenia

BACKGROUND

The presence of a hypercoagulable disorder such as heparin-induced thrombocytopenia (HIT) may protect against anticoagulant-associated bleeding.

OBJECTIVES

To determine the incidence of major bleeding in patients with suspected HIT.

METHODS

We performed a retrospective analysis of 310 patients suspected of having HIT from the Hospital of the University of Pennsylvania and an affiliated community hospital. We compared the cumulative incidence of major bleeding following suspicion for HIT by ultimate HIT status (HIT+ or HIT-) and exposure to an alternative anticoagulant (Tx+ or Tx-). Secondary outcomes included the incidence of new/progressive thrombosis and 30-day mortality.

RESULTS

The incidence of major bleeding was high in the HIT+Tx+, HIT- Tx+, and HIT-Tx- groups (35.7%, 44.0%, and 37.3%, respectively). The time to first major bleeding event did not differ between groups (P = .24). Factors associated with increased risk of major bleeding included intensive care unit admission (HR 2.24, 95% CI 1.44-3.47), platelet count < 25 × 109 /L (HR 2.13, 1.10-4.12), and renal dysfunction (HR 1.56, 1.06-2.27); 35.7% of HIT+Tx+, 13.8% HIT-Tx+, and 9.3% of HIT-Tx- patients experienced new or progressive thrombosis. Mortality was similar among the three groups (26.2% HIT+Tx+, 34.5% HIT-Tx+, and 26.7% of HIT-Tx- [P = .34]).

CONCLUSIONS

Among patients with suspected HIT, major bleeding was common regardless of HIT status. Contrary to our hypothesis, HIT+ patients were not protected from major bleeding. A better understanding of bleeding risk is needed to inform management decisions in patients with suspected HIT.

Prospective comparison of the HEP score and 4Ts score for the diagnosis of heparin-induced thrombocytopenia

The HIT Expert Probability (HEP) score compared favorably with the 4Ts score in a retrospective study. We assessed the diagnostic accuracy of the HEP score compared with the 4Ts score in a prospective cohort of 310 patients with suspected heparin-induced thrombocytopenia (HIT). A member of the clinical team calculated the HEP score and 4Ts score. An independent panel adjudicated HIT status based on a clinical summary as well as the results of HIT laboratory testing. The prevalence of HIT in the study population was 14.7%. At a cutoff of ≥3, the HEP score was 95.3% sensitive (95% confidence interval [CI], 84.2-99.4) and 35.7% specific (95% CI, 29.8-42.0) for HIT. A 4Ts score of ≥4 had a sensitivity of 97.7% (95% CI, 86.2-99.8) and specificity of 32.9% (95% CI, 27.2-39.1). The areas under the receiver operating characteristic (ROC) curves (AUCs) for the HEP score and 4Ts score were similar (0.81 [95% CI, 0.74-0.87] vs 0.76 [95% CI, 0.69-0.83]; P = .12). The HEP score exhibited a significantly higher AUC than the 4Ts score in patients in the intensive care unit (ICU) (0.86 vs 0.79; P = .03). Among trainee scorers, the HEP score performed significantly better than the 4Ts score (AUC, 0.80 vs 0.73; P = .03). Our data suggest that either the 4Ts score or the HEP score may be used in clinical practice. The HEP score may be preferable in ICU patients and among less experienced clinicians.

HITs and misses in 100 years of heparin

Heparin was discovered 100 years ago, and the heparin-induced thrombocytopenia syndrome was described 40 years ago. That the most powerful anticoagulant of the last century can also produce the most extreme prothrombotic diathesis is but one of the paradoxes that surround heparin-induced thrombocytopenia. Standard treatment is alternative anticoagulation. Advances continue to be made regarding pathophysiology, prevention, and treatment. Currently, an epidemic of overdiagnosis threatens the well-being of patients, so efforts to educate clinicians on when and how to make this diagnosis are pressing.